S/MIME Version 3 Message Specification
RFC 2633
| Document | Type |
RFC - Proposed Standard
(June 1999; Errata)
Obsoleted by RFC 3851
Was draft-ietf-smime-msg (smime WG)
|
|
|---|---|---|---|
| Last updated | 2013-03-02 | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 2633 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | (None) | ||
| Send notices to | (None) | ||
Network Working Group B. Ramsdell, Editor
Request for Comments: 2633 Worldtalk
Category: Standards Track June 1999
S/MIME Version 3 Message Specification
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (1999). All Rights Reserved.
1. Introduction
S/MIME (Secure/Multipurpose Internet Mail Extensions) provides a
consistent way to send and receive secure MIME data. Based on the
popular Internet MIME standard, S/MIME provides the following
cryptographic security services for electronic messaging
applications: authentication, message integrity and non-repudiation
of origin (using digital signatures) and privacy and data security
(using encryption).
S/MIME can be used by traditional mail user agents (MUAs) to add
cryptographic security services to mail that is sent, and to
interpret cryptographic security services in mail that is received.
However, S/MIME is not restricted to mail; it can be used with any
transport mechanism that transports MIME data, such as HTTP. As such,
S/MIME takes advantage of the object-based features of MIME and
allows secure messages to be exchanged in mixed-transport systems.
Further, S/MIME can be used in automated message transfer agents that
use cryptographic security services that do not require any human
intervention, such as the signing of software-generated documents and
the encryption of FAX messages sent over the Internet.
1.1 Specification Overview
This document describes a protocol for adding cryptographic signature
and encryption services to MIME data. The MIME standard [MIME-SPEC]
provides a general structure for the content type of Internet
messages and allows extensions for new content type applications.
Ramsdell Standards Track [Page 1]
RFC 2633 S/MIME Version 3 Message Specification June 1999
This memo defines how to create a MIME body part that has been
cryptographically enhanced according to CMS [CMS], which is derived
from PKCS #7 [PKCS-7]. This memo also defines the application/pkcs7-
mime MIME type that can be used to transport those body parts.
This memo also discusses how to use the multipart/signed MIME type
defined in [MIME-SECURE] to transport S/MIME signed messages. This
memo also defines the application/pkcs7-signature MIME type, which is
also used to transport S/MIME signed messages.
In order to create S/MIME messages, an S/MIME agent has to follow
specifications in this memo, as well as the specifications listed in
the Cryptographic Message Syntax [CMS].
Throughout this memo, there are requirements and recommendations made
for how receiving agents handle incoming messages. There are separate
requirements and recommendations for how sending agents create
outgoing messages. In general, the best strategy is to "be liberal in
what you receive and conservative in what you send". Most of the
requirements are placed on the handling of incoming messages while
the recommendations are mostly on the creation of outgoing messages.
The separation for requirements on receiving agents and sending
agents also derives from the likelihood that there will be S/MIME
systems that involve software other than traditional Internet mail
clients. S/MIME can be used with any system that transports MIME
data. An automated process that sends an encrypted message might not
be able to receive an encrypted message at all, for example. Thus,
the requirements and recommendations for the two types of agents are
listed separately when appropriate.
1.2 Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [MUSTSHOULD].
1.3 Definitions
For the purposes of this memo, the following definitions apply.
ASN.1: Abstract Syntax Notation One, as defined in CCITT X.208.
BER: Basic Encoding Rules for ASN.1, as defined in CCITT X.209.
Certificate: A type that binds an entity's distinguished name to a
public key with a digital signature.
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